With modern, premium ammo, all of the "service" cartridges (.38 Spl +P, 9mm, .357 Sig, .40 S&W, .45 GAP, and .45 ACP) perform much more alike than differently and that is because they are designed to. Nearly all of these cartridges will reliably expand to 1.5-2x original diameter and penetrate 12-16" in both bare gelatin and gelatin covered with four layers of denim. The real differences in how these cartridges perform is not in their terminal ballistics, but in their performance after penetrating intermediate barriers such as sheet steel, auto glass, ply wood, and sheet rock and in how quickly and accurately the shooter can fire them. Most people are best armed with whichever of the above cartridges they can shoot the most quickly and accurately from their chosen handgun.